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BQ40Z50-R2: Status LEDs not illuminating

Matt Regan
Prodigy 20 points
Part Number: BQ40Z50-R2
Other Parts Discussed in Thread: BQSTUDIO, BQ40Z50, BQ40Z50-DEVICE-FW

Hello,

I cannot get the status LEDs to illuminate under any condition other than sending LED toggle, in which case all LEDs illuminate as expected. The client wants LEDs to illuminate during charging and when the pack is turned on.

Nothing illuminates during charging, although the battery % displayed on BQ studio seems off and intermittent so I suspect it hasn't calibrated correctly, despite selecting the correct chemistry and running a learning cycle. (Qmqx for cells 1 and 2 seems to have been set, for the unused cells 3 and 4 it obviously didn't change, but is still 4400mAh, should I clear this? Qmax pack seems correct. The pack is currently charging. No LEDs and BQstudio shows 0% charge despite it being 7913mV (2S 18650)

I cannot get the LEDs to illuminate upon exit of reset either. I suspect it may be the same issue and the chip for some reason always thinks it is empty so it IS "illuminating" 0 LEDs

The board does not utilize the DISP button, so the pin is connected to VSS, so unfortunately I cannot test it that way, and, sending DISPLAY_PRESS from BQ studio does nothing.

Lastly, the client very specifically wants only 1 switch for on/off of the pack, and the LEDs to illuminate on power ON and charge. They do NOT want a display button. I thought I could get around this by using a switch on pin 16 and using it to enter shutdown mode, but missed the part where it is changing state based on a falling edge, so the switch must be cycled like a push button. Is it possible to configure the chip to enter shutdown when pin 16 is pulled low and exit shutdown when it is released (instead of using the falling edge transition)? Otherwise if setting NR to 0 and using the pin/switch for pack detection, is there a way to illuminate LEDs when the pack is "inserted"/switched on?

Thank you!

  • 0
    TI__Mastermind 28440 points

    Hi Matt,

    If possible, can you please send the .gg file of the gauge so we take a look into the settings?

    Just to confirm, are the LEDs that are being used set up in the same configuration as below or differently?

    Regards,

    Anthony Baldino

  • 0 in reply to Anthony
    Prodigy 20 points

    Sorry for the delayed response, Anthony.

    Here is the exported file from the data memory tab, I am assuming that's what you want to look at. If not I can upload whatever else you need.

    Is there a way to "factory reset" the chip and start over from default values? Also, does TI provide a quickstart guide for initial setup and cell configuration? Combing the registers and their proper settings in the URM is a bit sporadic so I may have missed something.

    Thank you for your help!

    Battery_no_LED.gg.csv

  • 0 in reply to Matt Regan
    TI__Mastermind 28440 points

    Hi Matt,

    Thank you for sending that over. 

    Matt Regan said:
    Is there a way to "factory reset" the chip and start over from default values?

    Yes, this can be done by going to the bq40z50 product page below, going to bq40z50-DEVICE-FW under Software Development, and downloading. This will give you a fresh .srec file that can be programmed to the gauge in bqStudio's Firmware Tab.

    I believe for cell configuration, the most important parameter to change is DA Configuration, which can be done in bqStudio in this register:

    For initial set up, I believe the best place to start is conducting the learning cycle. How this is accomplished can be found below:

    https://www.ti.com/lit/pdf/slua903 

    In this process as well, you will need to chose a chemID. The tool to assist with this can be found here:

    https://www.ti.com/tool/GPCCHEM 

    Regards,

    Anthony Baldino

  • 0 in reply to Anthony
    Prodigy 20 points

    Thanks,

    I am going to start fresh on a second control board. Did you find anything in the gg file I sent? It should have CC1 = 0 CC0 = 1 for  a 2 cell pack and I have done the ChemID as well as a learning cycle with no luck, that's what led me to ask here.

    Edit: I also forgot to mention that the image in your first reply is broken.

  • 0 in reply to Matt Regan
    TI__Mastermind 28440 points

    Hi Matt,

    Sorry about that, please let me know if you can see the configuration below:

    Also within the LED Configuration, can you please confirm that LEDC0 and LEDC1 are configured correctly for the LEDs you are using?

    Regards,

    Anthony Baldino

  • 0 in reply to Anthony
    Prodigy 20 points

    Yes, they are configured the same (this schematic has A,B, and C in reverse order on the chip, but the connections are correct)

    LEDC0 and LEDC1 are both 0. The LEDs all illuminate correctly when the LED toggle command is issued, but never otherwise. Even if LED_EN is set.

  • 0 in reply to Matt Regan
    TI__Mastermind 28440 points

    Hi Matt,

    Thank you for confirming those topics.

    Matt Regan said:
    It should have CC1 = 0 CC0 = 1 for  a 2 cell pack and I have done the ChemID as well as a learning cycle with no luck, that's what led me to ask here.

    I see that this was stated earlier. When you say you did the ChemID and learning cycle with no luck, do you mean this did not fix the issue or was the learning cycle not able to complete?

    Typically, the learning cycle is where the gauge learns all of the necessary parameters about the cell in use, which are used in SOC, FCC, and Remaining Capacity calculations. If this was not done correctly, then this could point to why the LEDs are at least not toggling during SOC changes.

    Regards,

    Anthony Baldino

  • 0 in reply to Anthony
    Prodigy 20 points

    Sorry again for the delayed response! The pack got shuffled to the back shelf for a bit. I believe there was a hardware issue with the sense resistor. The pack % would appear fine after a reset, my guess is based off of voltage, but would not track well during charge or discharge. I think the learning cycles were failing as well. 

    The board was revised and we are currently waiting for it to come back from fab for further testing. A button for the disp pin was also added to hopefully between the two the problem will be resolved. I will try to remember to report back!

  • 0 in reply to Matt Regan
    TI__Mastermind 28440 points

    Hi Matt,

    Thank you for the update, please let us know if there are any issues after testing.

    Regards,

    Anthony Baldino

  • 0 in reply to Anthony
    Prodigy 20 points

    Pack seems to be working now. Although if the DISP pin is held, it preempts the gauge while charging functionality, but that is unrelated.

  • 0 in reply to Matt Regan
    TI__Mastermind 28440 points

    Hi Matt,

    Thank you for the update, please let us know if any other issues come up.

    Regards,

    Anthony Baldino